In 1991, after the Soviet Union collapsed, the United States gained unchallenged supremacy in the world. Indeed, just three years later, the U.S. alone accounted for about 25 percent of global GDP and 40 percent of world military spending, while Washington's treaty allies in Europe and the Asia Pacific boasted roughly another 47 and 35 percent, respectively. Potential adversaries, meanwhile, were weak and overmatched: Russia was reeling from the Soviet implosion; China did not have the economic or military weight to compete; Iran was still recovering from its calamitous war with Iraq. In this environment, the U.S. could act with impunity. Democracy was expanding across the globe; the long shadow of communist authoritarianism had disappeared. It was the end of history as we knew it. Or so many thought.

That post-Cold War era has now passed. What comes next is still taking shape, but one thing is clear: America's relative dominance is declining. U.S. shares of global GDP and defense spending are, while formidable, not what they once were; the same goes for Washington's core treaty allies. More importantly, the U.S. and its Western allies have been reluctant to use their still-considerable power assertively. At the same time, hostile authoritarian states have pursued in earnest their long-held ambitions to dominate their own regions. These revisionist powers—Russia in Europe, China in East Asia, and Iran in the Middle East—never accepted the world order that followed the Cold War, defined by an open global economic system, international institutions, liberal political norms, and American supremacy. So Moscow, Beijing, and Tehran bided their time, gaining strength and waiting for the right time to try to overturn the order. That time has arrived, and the implications for American interests and global peace and stability are profound—and quite dangerous.

Fortunately, the American Enterprise Institute has published a collection of essays to help the West confront this new challenge. Rise of the Revisionists, edited by AEI scholar Gary Schmitt, attempts "to spell out the specific nature" of Russia, China, and Iran's "revisionist drive[s] and how, broadly speaking, the U.S. and its allies should respond." The volume features three smart and penetrating essays—Frederick Kagan's "Russia: The Kremlin's Many Revisions," Dan Blumenthal's "China: The Imperial Legacy," and Reuel Marc Gerecht's "Iran: The Shi'ite Imperial Power"—which concisely analyze "the roots and the character" of each country's revisionist efforts.

As Schmitt notes in his introduction, one cannot cram Russia, China, and Iran's revisionist drives into one "overarching model." They share similar ambitions, but each has its own agenda and motivations. In the case of Russia, Kagan argues that, through its behavior, Moscow wants to "revise" its agreements with other former Soviet states, the very meaning of "Russia" and "Russian" identity, and the international order. These three factors drive Vladimir Putin's aggressive actions today. As for China, Blumenthal writes that the People's Republic is intent on revising the balance of power in East Asia to dominate the region (with more global ambitions to follow if successful). China's rise is a resurgence to power, with its "imperial history as the central power in Asia" driving its efforts to pursue a system in which "the territories it claims and the countries that contest them should be deferential to the Middle Kingdom." With Iran, Gerecht writes that, after the regime lost the "mojo" of its broader Islamic revolutionary agenda, Tehran shifted to a narrower "militant Shi'ite fraternity," meant to strengthen the regime's domestic position and advance its drive for regional preeminence. The Islamic Republic plays on Shi'ite resentments across the Middle East to gain influence and recognizes that it still has a "vibrant Shi'ite identity" to "motivate the faithful and undermine critics who stopped believing in the cleric-constructed Islamic state," despite the secularization of Iranian society.

While these essays discuss external factors like military strategy and force posture, they are, at their heart, about each country's internal dynamics. This is one of the book's great insights: that domestic politics and regime type are crucial to understanding the nature and origin of each country's revisionist drive, which in turn is essential to forming effective policies to counter their belligerence abroad.

Walter Russell Mead makes this point clear in his concluding essay. He uses Thucydides' timeless History of the Peloponnesian War to show how the two dominant theories in American foreign policy—liberalism and realism—are flawed. The liberal argument—that more democracy and economic interdependence will lead to less conflict and more cooperation—is easy to criticize after history did not end with the post-Cold War era. What is particularly welcome about Mead's essay is his criticism of realism—especially by using Thucydides, who international relations realists revere as their paragon. Modern realists, Mead writes, have created a form of realism that is a "weak and denatured creature, compared to the complex vision of Thucydidean realism, and the costs to analytic coherence are serious. No concept could be less congenial to Thucydides than the idea that domestic politics and regime type are largely irrelevant to the study of international relations." It is necessary to know what impels states and their leaders to act as they do, but also to recognize that, even with such knowledge, human beings cannot be "counted on to behave like rational actors."

Another reason why Rise of the Revisionists is a welcome work: the authors say the West must confront and weaken, not accommodate, Russia, China, and Iran. "Policies designed to satiate each of the three countries have not worked," Schmitt notes. This view, supported by history, underpins much of the authors' recommendations for how the U.S. and its allies should respond to the revisionists' belligerence. Each scholar also understands that America, while not as dominant as it once was, is still the world's only superpower, and far more powerful than any would-be challenger. They recognize that "decline is a choice," and that much of America's perceived weakness is of its own making (e.g., cuts in defense spending) and its unwillingness to exercise power (e.g., Obama's red-line debacle in Syria).

Of course no one should want war, but war is less likely if Washington establishes credible deterrence. Moreover, the U.S. and its allies must impose costs—military, economic, and political—on the revisionists for their actions, while offering a path to peace and prosperity if they change their behavior.

Why should we care about any of this? It is true that none of the three states appears poised to attack the American homeland. But the notion that the world will somehow settle into spheres of influence that maintain stability is folly. First, the foundation of American strategy has long been to prevent a hostile state, or group of states, from dominating Europe, East Asia, or the Middle East—where they could gain enough power to threaten America's vital interests. Second, history shows that not addressing such threats sooner makes it much bloodier to address them later. Third, the U.S. does not operate in a vacuum. If Washington does not move to counter a revisionist power, states in that region will either appease the belligerent, only emboldening it to seek more, or resist, leading to chaos and potential conflict that would draw in the U.S. anyway. Fourth, the three revisionists threaten U.S. allies, which must be protected. Allies exponentially boost the U.S. economy (there would be no Samsung Galaxy smartphone without U.S. troops in South Korea, for example), American military power (the U.S. could not win wars outside the Western hemisphere without allied bases), and deterrence ("Alliances are not to be measured in dollars, but in their effectiveness at deterring conflict," Allan R. Millett, a prominent military historian, once said). Fifth, the U.S.-led world order has created unprecedented global peace and prosperity, benefiting America more than anyone. Russia, China, and Iran, all governed by cruel and oppressive regimes, will fundamentally change this system for the worst if they have their way. Sixth and finally, U.S. policymakers should care about leaving their children a decent world in which large countries do not bully small ones, human rights are respected, and democracy has a chance to flourish. If America does not try, no one else will.

Amid the chaos set to ensue in a new and dangerous world, American leaders must remember that they are on the right side of these international issues. Henry Kissinger said in 1982 that, in its foreign policy, "Britain has traditionally practiced a convenient form of ethical egoism, believing that what was good for Britain was best for the rest." This self-confidence, passed down to Britain's most famous former colony, should be the basis of U.S. foreign policy going forward, with the country ready to stand up to any hostile revisionist powers looking to supplant the remarkable historical aberration that is American supremacy.

Aaron KliegmanEmail | Full Bio | RSSAaron Kliegman is the news editor of the Washington Free Beacon. Prior to joining the Free Beacon, Aaron worked as a research associate at the Center for Security Policy, a national security think tank, and as the deputy field director on Micah Edmond's campaign for U.S. Congress. In December 2016, he received his master's degree from Johns Hopkins University’s Global Security Studies Program in Washington, D.C., with a concentration in strategic studies. He graduated from Washington and Lee University in 2014 and lives in Leesburg, Virginia. His Twitter handle is @Aaron_Kliegman. He can be reached at kliegman@freebeacon.com.